KR20060079957A - Soft conformable photomask for photolithography, process for preparing the same, and fine pattering process using the same - Google Patents

Abstract

The present invention relates to a flexible photomask for photolithography, a method of manufacturing the same, and a pattern forming method employing the same. Specifically, the present invention relates to a flexible photomask for photolithography having a pattern formed on one surface thereof, a method of manufacturing the same, and a pattern forming method employing the same.

Description

Soft photomask for photolithography, manufacturing method thereof, pattern formation method employing the same {Soft conformable photomask for photolithography, process for preparing the same, and fine pattering process using the same}

1 is a schematic diagram illustrating a photolithography process according to the prior art.

2 shows a schematic cross-sectional view of a photomask according to the prior art.

3A is a schematic diagram illustrating a general photolithography process according to the present invention.

3B is a schematic diagram illustrating a process of forming a metal pattern on a flexible substrate as an example of a photolithography process according to the present invention.

4A shows an example of a soft photomask according to Example 1 of the present invention.

4B shows an example of a soft photomask according to Embodiment 2 of the present invention.

4C shows an example of a soft photomask according to Embodiment 3 of the present invention.

5 shows an optical micrograph of a metal pattern obtained according to the present invention.

6 shows an optical micrograph of a metal pattern obtained according to the present invention.

Fig. 7 shows an optical micrograph of an electrode for organic electroluminescent elements obtained according to the present invention.

8 is a schematic cross-sectional view of an organic EL device according to the present invention.                 

9 is a schematic cross-sectional view of an organic EL device according to the present invention.

10 is a schematic cross-sectional view of an organic EL device according to the present invention.

11 is a schematic cross-sectional view of an organic EL device according to the present invention.

* Brief description of symbols used in drawings

11: substrate 12; Photoresist

13: transparent substrate 14: pattern layer

15: photoresist layer of exposure area

16: photomask

20: photomask 21: transparent substrate

22 pattern layer 23 polymer thin film layer 24 gap

31 substrate 32 photoresist 33 soft photomask

34: pattern (after exposure) 35: metal layer 36: light impermeable layer

41: substrate 42: transparent electrode (anode) 43: metal electrode (anode)

44 (44a and 44b): organic layer 45: hole transport layer 46: electron transporting light emitting layer

47: hole transporting light emitting layer 48: electron transporting layer

49 hole transport layer 50 light emitting layer 51 electron transport layer

The present invention relates to a flexible photomask for photolithography, a method of manufacturing the same, and a pattern forming method employing the same. Specifically, the present invention relates to a flexible photomask for photolithography having a pattern formed on one surface thereof, a method of manufacturing the same, and a pattern forming method employing the same.

Electrode manufacturing processes and semiconductor manufacturing processes of many display devices are made by photolithography manufacturing processes and the like. The method of forming the fine pattern layer of the photoresist material on the substrate generally proceeds as follows. A layer of photoresist material is first formed on the surface of the substrate in direct contact with a photomask having a pattern of masking material. By irradiating the photoresist layer through the masking material layer with ultraviolet rays or the like, the solubility behavior of the photoresist material is modified in an exposure area to obtain a latent image having a fine pattern of the photomask.

When the solubility of the photoresist is increased by exposure, when it is dissolved in processing with a developer liquid, the photoresist is called a positive method. On the other hand, when the photoresist material becomes insoluble by exposure, such a photoresist is called a negative method since the photoresist material in the exposed area is selectively dissolved and removed by the developer liquid. In both cases, the developing process uses the solubility difference between the exposed and non-exposed areas to form a latent image on the substrate.

In recent years, as the degree of integration of electrodes of a display element and a semiconductor element is rapidly increased, higher resolution is required in patterning obtained by the above-described method. As is known, repeated photolithographic patterning processes of several to ten times are used in the manufacturing process of fine electrical components such as most display devices and semiconductor devices. Each process involves a chemical etching process that roughens the surface of the photoresist layer, so that the accuracy of reproducing the fine pattern of the photomask cannot be as high as that required for the photoresist layer.

In addition, as shown in FIG. 1, a vacuum or a pressure is applied to compress the photoresist layer 12 and the photomask 16. Through this, the close contact between the photoresist layer 12 and the photomask 16 is completely achieved. There is a problem that is not made. That is, in a conventional photolithography process, the photoresist layer 12 is formed on the substrate 11, and then, by depositing a metal 14 such as chromium on a hard substrate 13 such as a glass or a transparent substrate. The photomask 16 is exposed after contact with the photomask 16. In this process, even if a vacuum or pressure is applied between the photomask 16 and the photoresist layer 12, there is a problem in that resolution is inevitably reduced since no perfect adhesion is formed therebetween.

In order to solve this problem, U.S. Patent No. 4,735,890 (Applicant: Nakane et al.) Describes a content of strengthening adhesion by applying a polymer material on a photomask. However, in the case of the above document, the adhesion is possible to some extent, but the gap between the pattern 22 of the photomask and the photoresist layer is still due to the polymer layer 23 applied on the photomask 20 as shown in FIG. 2. 24) occurs, causing a decrease in resolution. This, in turn, is a limitation of the degree of integration, resulting in a reduction in working accuracy.

In addition, the aforementioned methods have a limitation in that they cannot be applied to flexible substrates, and there is a need for further improvement.

The technical problem to be achieved by the present invention is that there is no problem of the prior art using a conventional photomask, and a soft photomask for photolithography and a method for manufacturing the same, which provide high resolution to form fine patterning on the photoresist layer. To provide.

Another object of the present invention is to provide a fine patterning method employing the photomask.

The present invention to achieve the above technical problem,

It is made of a light-transmitting elastomer, and provides a soft photomask for photolithography in which a pattern is formed on one surface thereof.

The light-transmitting elastomer is a polymer having a glass transition temperature of less than room temperature as a silicone rubber such as polydimethyl siloxane, nitrile rubber, acrylic rubber, polybutadiene, polyisoprene, butyl rubber, poly (styrene-co-butadiene), etc. This is possible.

The photomask may further form a light impermeable layer, respectively, on the concave portion or the concave portion of the pattern formation surface.

The photomask may be formed by forming a pattern with a light impermeable layer on the surface of the light-transmitting elastomer that is not formed with a pattern.                     

As the light impermeable layer, a metal layer, an organic material layer, or the like can be used.

The organic material layer may be a low molecular layer, a polymer layer, a carbon black layer, a silver paste layer, or the like.

As the organic layer, one having a light absorption band of 200 to 450 nm may be used.

As the metal forming the metal layer, an opaque metal such as Au, Ag, Cr, Al, Ni, Pt, Pd, Ti, Cu, or the like is possible.

The thickness of the light impermeable layer is preferably 1 to 500 nm, more preferably 5 to 100 nm.

The photomask may be formed by forming a pattern with a light impermeable layer on the surface of the light-transmitting elastomer that is not formed with a pattern. That is, the pattern forming material formed on the photomask is the light transmitting elastomer or metal.

It is preferable that the thickness of the pattern formed in the said photomask is 100 nm-1 micrometer.

The present invention to achieve the above other technical problem,

Manufacturing a master substrate having a pattern formed thereon;

Adding a mixture of a silicon-based elastomer precursor and a crosslinking agent on the master substrate; And

After polymerizing the silicon-based elastomer precursor, it provides a method for producing a flexible photomask for photolithography comprising the step of separating the mask formed on the master substrate.

Depositing a metal on a surface on which a pattern on the formed mask is formed; And

And removing the metal layer formed on the convex portion.

In the manufacturing method, the method further comprises the step of contacting the adhesive polymer solution, carbon black paste or silver paste on the surface of the concave portion in which the pattern on the formed mask is formed.

Another method of manufacturing the flexible photomask for photolithography,

Forming a silicon-based elastomer layer;

Adhering a shadow mask on the layer; And

Vacuum depositing a metal or organic material.

The present invention to achieve the above another technical problem,

Forming a photoresist layer on the base substrate;

Contacting the surface on which the pattern of the soft photomask according to any one of claims 1 to 11 is formed with the photoresist layer by soft close contact; And

It provides a fine pattern forming method comprising the step of exposing to form a pattern.

Before the photoresist layer is formed, a metal layer for pattern formation is first formed, and thereafter, the metal layer is etched using the patterned photoresist layer, and further comprising removing the photoresist layer. Pattern formation methods are possible.

The base substrate may be glass, plastic, rubber, or an elastomer, and the base substrate is preferably a silicone-based elastomer.

It is preferable that the said metal layer for pattern formation contains an adhesion promoter layer.

In the metal layer for pattern formation, the first layer is an adhesion promoter layer, and the thickness is preferably 0.5 to 10 nm, and the metal to be used is preferably Ti or Cr. The second layer is a metal layer and a thickness of 5 to 100 nm is preferable, and the metal used is preferably Au, Ag, Al, Pd, Pt, or the like.

The present invention to achieve the above another technical problem,

Provided is an electrode for a display device comprising a fine pattern formed according to the above method.

Hereinafter, the present invention will be described in more detail.

The present invention provides a photomask useful in a photolithography process, wherein the photomask of the present invention is made of a soft conformal type material to facilitate adhesion to the surface of the photoresist layer. As such a material, a light-transmitting elastomer is used. When manufacturing a flexible photomask for photolithography using such a material, Van der Waals interacts with the surface of the photoresist layer formed on the substrate. interaction) enables contact at the molecular level, resulting in stronger adhesion between the photomask pattern and the photoresist layer.                     

The photomask according to the invention provides particularly useful in the case of performing lithography on a flexible type substrate by using a light transmissive elastomer. That is, glass, high quality silica glass, rigid plastics, etc. may be used, but flexible type substrates of soft materials such as soft plastics, elastomers, rubbers, and more specifically, for example, polyethylene terephthalate, polyethylene naphthalate, polyvinyl alcohol, polydimethyl Siloxane, polycarbonate, polyester, polyestersulfonate, polysulfonate, polyacrylate, fluorinated polyimide, fluorinated resin, polyacrylic, polyepoxy, polyethylene, polystyrene, polyvinylchloride, polyvinylbutyral, polyacetal, Polyamide, polyamideimide, polyetherimine, polyphenylene sulfide, polyethersulfone, polyetherketone, polyphthalamide, polyethernitrile, polybenzimidazole, polymethyl (meth) acrylate, polymethacrylamide , Epoxy resin, phenolic resin, melamine It is particularly useful when performing lithography on a substrate of a material such as resin, urea resin, nitrile rubber, acrylic rubber, polybutadiene, polyisoprene, butyl rubber, poly (styrene-co-butadiene) and the like. In the case of the flexible type substrate of such a soft material, if a metal pattern is formed on the substrate by a conventional photolithography process, cracks may occur between the metal and the photoresist layer, thereby making it difficult to use.

However, in the case of using the flexible photomask according to the present invention, since the photomask itself is made of a flexible type such as a light-transmitting elastomer, there is no fear of cracking of the applied metal and photoresist layer in the photolithography process, and thus flexible display. The flexible ITO layer for the electrode of the device and the pattern of the metal can be easily produced without damage such as cracks.

The photomask according to the present invention is made of a transparent elastomer that is a soft material, and has a structure in which a predetermined pattern is formed on one surface thereof. The pattern on the photomask may be formed integrally with the same component as the light-transmitting elastomer that is the base material. Alternatively, the pattern on the photomask may be formed of a separate metal layer or an organic material layer. That is, it is also possible to produce a flat mask having no pattern formed thereon and then form a pattern with a flat light impermeable layer on the surface thereof to form a photomask. That is, it is also possible to form a photomask by forming a pattern with a light impermeable layer on the surface thereof after preparing a flat light-transmissive elastomer having no pattern formed thereon.

The light-transmitting elastomer that is the material of the photomask is a polymer having a glass transition temperature of less than room temperature, polydimethylsiloxane (hereinafter referred to as PDMS), nitrile rubber, acrylic rubber, polybutadiene, polyisoprene, butyl rubber, poly (styrene) -Co-butadiene) and the like, but are not limited thereto. Due to the nature of the photomask, a material having excellent light transmittance is preferable because light must pass through an exposure process using light such as ultraviolet rays to cause a change in solubility on the photoresist layer. Good interaction is possible. Since the PDMS used in the present invention has all the above characteristics, it functions as the most preferable light-transmitting elastomer.

The flexible photomask according to the present invention may be formed of an integrated pattern of the same material as that of the base material, that is, a transparent elastomer, and in this case, in the exposure process, the light reaching the photoresist layer may be due to a difference in transmittance of light. The amount will be different. That is, as shown in FIG. 4A, when light is transmitted through the pattern on the photomask 33, it is reflected by encountering an air (refractive index = 1.0) layer having a low refractive index (refractive index> 1.5) and thus making soft contact with the photoresist. It is lower than the transmittance of light through the recessed pattern. Therefore, the solubility change of the photoresist layer is caused due to the difference in light transmittance in the exposure process. This change in solubility enables the photolithography process of negative or positive systems in the subsequent etching process.

Although the integrated soft photomask is also possible, as shown in FIGS. 4B and 4C, it is also possible to form the light impermeable layer 36 of the metal layer or the organic material layer in the pattern forming portion of the photomask. That is, the light impermeable layer may be further formed on the concave portion or the concave portion of the pattern formation surface. In the case where the soft photomask according to the present invention is an integral type in which a pattern is formed of a material such as a base material, as described above, the light transmittance at the recess is greater than that at the recess, and a separate light impermeable layer is formed at the recess or the recess. In the case of forming, the light transmittance is high only in other portions where the light impermeable layer is not formed, and thus more light such as ultraviolet rays passes through. More specifically, in the case where the light impermeable layer is formed on the concave portion (FIG. 4B), that is, when the light impermeable layer is formed only in the concave portion, not the portion in which the pattern is formed, the light does not pass through the concave portion. Only light passes through the formed protrusions. This is possible because the pattern is a light transmissive elastomer according to the invention. This difference in light transmittance causes a difference in solubility in the etching solution between the lighted portion and the unlighted region on the photoresist layer. In this case, the concave portion of the concave portion may be a metal layer or an organic material layer as a light impermeable layer, it is preferable to form a metal layer.

Alternatively, as shown in FIG. 4B, a light impermeable layer may be formed on the patterned protrusions of the photomask, that is, the protrusions of the concave portions. In this case, since light is difficult to pass through at the portion where the pattern is formed, it is difficult to pass. Therefore, light is transmitted on the portion where the pattern is not formed on the photoresist layer. The solubility difference will occur in the concave portion of the concave portion described above.

As the metal for forming such an opaque layer, opaque metals such as Au, Ag, Cr, Al, Ni, Pt, Pd, Ti, and Cu are possible, and as the organic material layer, a low molecular weight, a polymer having a light absorption band of 200 to 450 nm, Carbon black, silver paste, etc. are possible. In particular, an organic material layer having low light transmittance is preferable in the manufacturing process. Even when the above-mentioned light impermeable layer is formed in the convex portion (projection portion), van der Waals intermolecular interaction with the photoresist layer, which is a feature of the present invention, is possible.

The thickness of the light impermeable layer formed on the soft photomask according to the present invention is preferably 1 to 500 nm. If the thickness is less than 1 nm, the effect as a light impermeable layer is insignificant, and even if it exceeds 500 nm, it is not necessary to form a thicker film since it continues to maintain light impermeability.                     

In addition, the height of the light transmitting elastomeric pattern formed on the soft photomask according to the present invention is preferably 100 nm to 1 μm, more preferably 300 to 500 nm. If the height of the pattern is less than 100 nm, there is a problem such as sagging. If the thickness exceeds 1 μm, there is a problem such as collapse of the pattern, which is not preferable.

A method of manufacturing the soft photomask according to the present invention as described above is as follows.

That is, in the manufacturing method, a master substrate on which a pattern is formed is prepared, a mixture of an elastomeric precursor and a crosslinking agent is added to the master substrate, and then the elastomeric precursor is polymerized to form a mask formed on the master substrate. It includes a step.

The above-described manufacturing method will be described in more detail. First, as a manufacturing method of a soft photomask in which a pattern is integrated with a base material, a master substrate having a pattern is first manufactured. Such a master substrate can be made of a material such as glass, high quality silica glass, plastic, silicon wafer, etc., and can be produced by conventional methods. As such a conventional method, it is possible to use methods such as photolithography, electron beam lithography, nanoimprint lithography, molding and two-photon lithography. The obtained master substrate is placed in a wide bottom vessel such as a petri dish so that the pattern faces upward, and then an elastomer precursor is applied to the vessel so as to cover the master substrate. The precursor is polymerized by curing at a temperature of 60-100 ° C., preferably at a temperature of about 80 ° C. for at least 30 minutes, preferably 1 to 2 hours. The silicon-based elastomer formed after the polymerization is separated and cut into a predetermined size to prepare a soft photomask made of the silicon-based elastomer according to the present invention.

As the elastomeric precursor for preparing the photomask, many commercially available materials can be used. However, when the target product is PDMS, a crosslinking agent and a material such as PDMS precursor, for example, the brand name Sylgard 184 (available from Dow Corning), may be used. The mixture mixed in the ratio of 1 can be used. As the crosslinking agent, most substances known as ordinary crosslinking agents can be used without limitation.

The manufacturing method in the case where the light impermeable layer is formed on the soft photomask according to the present invention is as follows. The light impermeable layer can be formed on the concave portion (concave portion) or the concave portion (projection portion), respectively, and the manufacturing method thereof will be described.

First, as a method of forming a light impermeable layer in the concave portion of the concave portion, a soft photomask in which a pattern is formed as described above is manufactured, and then metal is entirely deposited on the surface on which the pattern is formed, and then the metal layer formed in the convex portion of the concave portion is removed. It consists of steps.

More specifically, gold, palladium, chromium, or the like is formed on the surface of the soft photomask formed by applying an elastomeric precursor to the patterned master substrate using a thermal deposition or electron beam deposition method to a thickness of about 1 to 500 nm. Deposit. In this case, the metal layer is formed by depositing both the portion where the pattern is formed and the portion where the pattern is not formed on the photomask. In order to remove the metal layer formed in the patterned portion and the protruding portion of the metal portion formed in this way, a cold-welding technique or chemical bonding using a strong adhesive force between the metal when the metal and the metal bonded at room temperature Nanotransfer printing (nanotransfer printing) and the like can be used. The cold-welding technique refers to a method of using an oxide layer and a phenomenon in which metals having a high work function adhere to each other when they are in contact with each other. The chemical bonding method combines an alkane dithiol series on a metal layer. Metal layer on the other side using these chemical bonds to transfer or lift-off due to the difference in bonding strength between the two substrates.

In the case of using a cold-welding technique to remove a part of the metal layer formed on the photomask, first, an adhesive layer such as Ti is formed on a substrate such as a silicon wafer or glass, and then to be removed therefrom. A metal layer of the same material as the metal is formed and the surfaces are brought into contact with each other with the metal layer to be removed of the photomask described above. In this case, the metals which are in contact with each other stick to each other, and when separated from each other, the metal formed in the pattern portion of the photomask is separated from the photomask due to the stronger tension of the adhesive layer. As a result, a soft photomask according to the present invention in which a metal layer is formed only on the concave portion (concave portion) is obtained.

Next, as a method of removing a metal layer by using a chemical bonding method, the alkane dithiol-based compound is brought into contact with the surface of the metal layer formed on the pattern portion of the photomask, and then bonded to the surface, and the thiol functional group on the opposite side of the alkane dithiol is added to another metal After bonding with the surface, it is removed to remove the metal layer of the photomask.

In the above, the method of forming the light impermeable layer by removing the metal layer formed on the pattern forming part of the soft photomask according to the present invention, that is, the concave part (protrusion part) to form a metal layer only on the concave part (concave part). Next, a method of forming the light impermeable layer only on the pattern forming portion of the soft photomask according to the present invention, that is, the concave portion (protrusion), will be described.

First, a viscous organic material layer, for example, a polymer layer, a carbon black layer, a silver face layer, or the like is formed on a substrate, and only the pattern forming portion of the soft photomask manufactured as described above, that is, the convex portion (projection portion), is Contact with viscous organics. In this case, the organic material is bonded to the surface of the pattern forming part to form a layer, thereby manufacturing a soft photomask according to the present invention in which a light impermeable layer is formed only on the convex part (projection part).

All the photomasks as described above are described based on the photomask in which the pattern and the base material are integrated. Alternatively, the photomask, which is a different material of the pattern itself, may be manufactured.

In other words, the use of the elastomer as the base material is the same, but the pattern formed on the flat elastomer is vacuum deposited with a metal or organic material using a shadow mask to form a metal or organic material layer having a pattern of 1 to 500 nm, more preferably 5 nm to 100 nm. It is also possible to manufacture the formed photomask.

As a method of forming a fine pattern on a target substrate using the flexible photomask of the present invention manufactured as described above, as shown in FIGS. 3A and 3B, the photoresist layer 32 is formed on the base substrate 31. After forming, the surface on which the pattern of the soft photomask 33 manufactured according to the present invention is formed is brought into contact with the photoresist layer 32 and then exposed to form a pattern. Alternatively, the pattern forming metal layer 35 may be selectively formed on the base substrate 31, and the photoresist layer 32 may be formed on the metal layer 35. Contacting the surface on which the pattern of the photomask 33 is formed with the photoresist layer 32 and then exposing the pattern to form a pattern, etching the metal layer 35 and removing the photoresist layer 34. .

In the case of a transmissive mold type photomask in which a pattern of the recesses and protrusions is formed or a photomask in which a light-impermeable material is selectively applied to the pattern mold, the protrusions are formed of photoresist and van der Waals forces. This is in close contact with the soft bonding, and the recesses do not come into contact with each other. In this state, the negative photoresist is irradiated with an appropriate amount of ultraviolet light to form a pattern of the photoresist in the shape of a recess, or conversely, the positive photoresist is irradiated with an appropriate amount of ultraviolet light to wash the recess of the photomask during development. It is also possible to form a pattern of remaining shapes after exiting. In the case of a soft photomask having recesses and protrusions without a light impermeable layer, the same pattern as the recesses remains or disappears (negative type) (positive type). In the case of a soft photomask having concave portions and protrusions with a light impermeable layer, the same pattern as the part without the light impermeable layer remains or disappears. In the case of a photomask in which a metal or organic pattern is formed on the surface of a flat elastomer mold, ultraviolet rays are irradiated to a transparent area except for the metal or organic pattern area, and the negative area remains as much as the negative area. It is washed away.

In the case of forming a fine pattern using the soft photomask manufactured according to the present invention as described above, there is no gap between the photoresist layer 32 and the pattern forming portion of the photomask 33, and Since intermolecular interactions are caused by van der Waals forces, adhesion occurs more strongly between the photomask 33 and the photoresist layer 32. In addition, since the photomask 33 itself is a flexible material of a flexible material, even when the substrate is flexible, the pattern 36 is easily formed so as to prevent defects such as cracks in the metal 35 and the photoresist layer 32. .

As the base substrate 31 used in the fine pattern forming method, glass, plastic, rubber, elastomer or the like can be used. In particular, it is preferable to use flexible materials such as polyethylene terephthalate, polyethylene naphthalate, polyvinyl alcohol, polydimethyl siloxane and the like.

The pattern forming metal layer 35 used in the fine pattern forming method preferably includes an adhesion promoter layer. The pattern forming metal layer has a first layer of 0.5 to 10 nm, more preferably 1 to 3 nm. It is most preferable to use an Au, Pd, Ag, or Pt layer of 5 to 100 nm, more preferably 5 to 20 nm, of Ti or Cr layer. If the thickness of the first layer is less than 0.5 nm, there is a problem that the adhesion is not good, if it exceeds 10 nm, even if it exceeds 10 nm already because the adhesion is the same, it is no longer necessary to deposit thick. When the thickness of the second layer is less than 5 nm, the conductivity is low, so it is difficult to use in an electrical device such as an electrode. When the thickness of the second layer exceeds 100 nm, it takes more time to perform wet etching and the edge of the pattern is not formed cleanly. There is no possibility.

The present invention also provides a microelectronic component such as an electrode of a semiconductor device or a display device through the above fine pattern forming method using the soft photomask according to the present invention. In particular, in the case of the display device, the demand for the flexible type is increasing gradually. As a countermeasure, the usefulness of the present invention is particularly high. For example, it is possible to use a photolithography process as described above when patterning a conductive material on a flexible substrate using a flexible photomask of the present invention with a pattern.

In particular, when using the pattern obtained in this way as an electrode of an organic electroluminescent element, a flexible display element is manufactured. This will be described in more detail below.

8 to 11 show the structure of the organic electroluminescent device of the present invention. As shown in FIG. 8, the organic electroluminescent device of the present invention may be formed in a multilayer form in which a substrate 41, a transparent electrode 42, an organic layer 44, and a metal electrode 43 are sequentially stacked.

The operating mechanism of the organic EL device generally includes a series of processes such as injection of holes and electrons from an electrode, generation of an electronic excited state by recombination of holes and electrons, and emission from an excited state. As shown in FIG. 2, the organic layer is disposed between two other electrodes. Herein, the organic layer exhibits excellent characteristics of the stacked type device in which the light emitting layer and the charge transport layer are combined, rather than the single layer type device including the light emitting layer. This is because an appropriate combination of the light emitting material and the charge transport material reduces the energy barrier when charge is injected from the electrode, and the charge transport layer binds the holes or electrons injected from the electrode to the light emitting layer region to balance the number of holes and electrons injected. Because it plays a role to achieve.

Accordingly, the organic layer is preferably an electron transporting layer / light emitting layer / hole transporting layer, an electron transporting layer / hole transporting light emitting layer, or a hole transporting layer / electron transporting light emitting layer, as shown in FIGS. 9 to 11. In this case, the hole transporting material used in the hole transporting layer or the hole transporting light emitting layer may include at least one selected from the group consisting of low molecular weight or high molecular weight polymers composed of a carbazole derivative, an arylamine derivative, a phthalocyanine compound, and a triphenylene derivative. The electron transporting material used in the electron transporting light emitting layer may include a quinoline derivative compound, a quinoxaline derivative compound, a metal complex compound, or an aromatic compound including nitrogen. Substances that can be used as the light emitting layer include phenylene-based, phenylene vinylene-based, thiophene-based, fluorene-based low molecules or polymers, metal complex compounds, nitrogen It may include an aromatic compound and the like.

Specifically, the organic electroluminescent device shown in FIG. 8 has a multilayer form in which a substrate 41, a transparent electrode (anode) 42, an organic layer 44, and a metal electrode (cathode) 43 are sequentially stacked. In this case, the substrate 41 is used to form an element, and a conventional material, for example, glass, plastic, rubber, elastomer, or the like may be used, but a flexible type may be used. In this case polyethylene terephthalate, polyethylene naphthalate, polyvinyl alcohol, polydimethyl siloxane, polycarbonate, polyester, polyestersulfonate, polysulfonate, polyacrylate, fluorinated polyimide, fluorinated resin, polyacrylic as described above , Polyepoxy, polyethylene, polystyrene, polyvinylchloride, polyvinylbutyral, polyacetal, polyamide, polyamideimide, polyetherimine, polyphenylene sulfide, polyethersulfone, polyetherketone, polyphthalamide, polyether Nitrile, polybenzimidazole, polymethyl (meth) acrylate, polymethacrylamide, epoxy resin, phenol resin, melamine resin, urea resin, nitrile rubber, acrylic rubber, polybutadiene, polyisoprene, butyl rubber, poly (Styrene-co-butadiene) and the like can be used. The transparent electrode (anode) 42 may use indium tin oxide (hereinafter, abbreviated as ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), or the like; As the metal electrode (cathode) 43, an electrode on which a metal pattern obtained according to the fine pattern forming method according to the present invention is formed may be used. In addition, the organic layer 44 may be configured in a single layer or a multilayer of two or more layers including a known light emitting material. Other compounds such as Alq ₃ , rubrene and the like can be added.

The organic electroluminescent device shown in FIG. 9 is a multilayer form in which a substrate 41, a transparent electrode (anode) 42, an organic layer 44a, and a metal electrode (cathode) 43 are sequentially stacked, among which an organic layer. 44a has a structure in which the hole transport layer 45 and the electron transporting light emitting layer 46 are stacked. Here, the substrate 41, the transparent electrode (anode) 42 and the metal electrode (cathode) 43 are as mentioned above. The hole transport layer 45 is a conventional hole transport material such as 4,4-bis [N- (1-naphthyl) -N-phenyl-amine] biphenyl (hereinafter abbreviated as α-NPD), N, N-diphenyl-N, N-bis (3-methylphenyl) -1,1-biphenyl-4,4-diamine (hereinafter abbreviated as TPD), poly- (N-vinylcarbazole) (hereinafter as PVCz) Abbreviated-name) etc. can be used individually or in mixture of 2 or more types, and 2 or more layers in which another layer was laminated may be sufficient. The electron transporting light emitting layer 46 may be added alone or in combination of two or more conventionally known electron transport materials, for example, Alq ₃ , rubrene, and the like. In addition, in order to improve device characteristics such as efficiency and lifespan, various hole injection layers or anode buffer layers such as copper phthalocyanine or the like are inserted between the anode 42 and the hole transport layer 45 as necessary, or the cathode 43 ) And an electron injection layer or a cathode buffer layer such as LiF, BaF ₂ , CsF ₂ , LiO ₂ , BaO, or the like may be inserted between the electron transport layer 46 and the electron transporting light emitting layer 46.

The organic electroluminescent device shown in FIG. 10 is a multilayered structure in which a substrate 41, an anode 42, an organic layer 44a, and a cathode 43 are sequentially stacked, where the organic layer 44a is a hole transporting light emitting layer 47. ) And the electron transport layer 48 are laminated. Here, the substrate 41, the transparent electrode (anode) 42 and the metal electrode (cathode) 43 are as mentioned above. The electron transporting layer 48 may be used alone or as a mixture of two or more types of conventionally known electron transporting materials such as Alq ₃ , rubrene, polyquinoline, and coliquinoxaline, and may be two or more layers in which other layers are laminated. In addition, various hole injection layers such as copper phthalocyanine or an anode buffer layer may be inserted between the anode 42 and the hole transporting light emitting layer 47 to improve device characteristics such as efficiency and lifespan, or the cathode ( It is also possible to insert various conventional electron injection layers or cathode buffer layers such as LiF, LiF, BaF ₂ , CsF ₂ , LiO ₂ , BaO and the like between 43) and the electron transport layer 48.

The organic electroluminescent device shown in FIG. 11 is a multilayer form in which a substrate 41, a transparent electrode (anode) 42, an organic layer 44b, and a metal electrode (cathode) 43 are sequentially stacked, wherein the organic layer ( 44b) has a structure in which a hole transport layer 49, a light emitting layer 50, and an electron transport layer 51 are stacked. Here, the substrate 41, the transparent electrode (anode) 42 and the metal electrode (cathode) 41 are as mentioned above. The hole transport layer 49 may be used alone or in combination of two or more of conventional hole transport materials, for example, α-NPD, TPD, PVCz, or the like, or may be two or more layers in which other layers are laminated. The electron transporting layer 51 may be used alone or in combination of two or more types of conventionally known electron transporting materials such as Alq ₃ and rubrene, and may be two or more layers in which other layers are laminated. In addition, in order to improve device characteristics such as efficiency and lifespan, various hole injection layers or anode buffer layers such as copper phthalocyanine or the like are inserted between the anode 42 and the hole transport layer 49 as necessary, or the cathode 43 may be used. Between the electron transport layer 51 and various conventional electron injection layers such as LiF, LiF, BaF ₂ , CsF ₂ , LiO ₂ , BaO, or a cathode buffer layer may be inserted. The material that can be used as the light emitting layer 50 is a low molecular or high polymer such as phenylene, phenylene vinylene, thiophene, fluorene, or a metal complex compound, Aromatic compounds containing nitrogen; and the like.

The above-mentioned organic electroluminescent elements (Figs. 8 to 11) of the present invention are driven by applying a voltage between the anode 42 and the cathode 43, and the voltage is usually using direct current, but pulse or alternating current may also be used. .

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples and Comparative Examples.

Example 1: Preparation of a Soft Photo Mask

A master substrate was produced by forming a pattern on a glass using a photolithography process according to a conventional method. The obtained master board | substrate was put on the petri dish with the pattern facing upwards, and the mixture which mixed PDMS precursor (brand name: Sylgard 184, Dow Corning Co., Ltd.) and a crosslinking agent in the weight ratio of 9: 1 was added to it. After the addition of the mixture, the mixture was cured at a temperature of 80 ° C. for 2 hours to polymerize. After the polymerization process was completed, the PDMS photomask was separated from the master substrate and cut to a desired size to obtain a soft photomask of a desired PDMS material.

Example 2 Preparation of Flexible Photomask with Metal Layer (Cold Welding Method)

In order to form a metal layer as a light-impermeable layer in the pattern non-formation portion in the concave portion of the PDMS photomask obtained in Example 1, Au was entirely deposited to an average thickness of 30 nm using the electron beam evaporation method. Separately, a Ti layer was deposited to a thickness of 2 nm on the silicon wafer as an adhesive layer, and then Au was deposited to a thickness of 30 nm. The Au layers of the photomask were contacted with each other on the Au layer formed on the silicon wafer, and then they were attached to each other within 30 seconds. Subsequently, the PDMS photomask was separated from the silicon wafer to selectively remove only the Au layer of the protruding portion of the pattern forming portion to prepare a PDMS photomask having a metal layer formed in the recess of the pattern.

Example 3 Preparation of Flexible Photomask with Metal Layer (Chemical Bonding Method)

In order to form a metal layer as a light impermeable layer on the pattern forming portion of the PDMS photomask obtained in Example 1, Au was entirely deposited to an average thickness of 30 nm using an electron beam deposition method. An octane dithiol solution (5 mM) was contacted to the surface of the protrusion on which the Au layer was formed so that the terminal portion of the octane dithiol was bonded to the Au layer. Separately, a Ti layer was deposited to a thickness of 2 nm on the silicon wafer as an adhesive layer, and then Au was deposited to a thickness of 30 nm. The PDMS photomask coated with Au was contacted on the substrate to bond opposite ends of the octane dithiol, and then separated to remove the Au layer of the protruding portion, thereby preparing a PDMS photomask having an Au layer formed on the pattern non-forming portion. .

Example 4 Soft Photomask with Carbon Black Layer Formed

In order to form a carbon black layer as a light impermeable layer on the protrusions of the PDMS photomask obtained in Example 1, after applying a thin layer of viscous carbon black on the substrate, immediately contacting the protrusions of the PDMS photomask to contact the protrusions The viscous carbon black layer was applied on the surface. This was dried to prepare a PDMS photomask having a carbon black layer formed on the protrusion.

Example 5: Pattern Formation on Flexible Substrate

A photoresist layer was formed on the glass substrate by a thickness of 400 nm using spin casting. The flexible photomask prepared in Example 1 was placed on the photoresist layer, exposed to 100 ㎼ / cm ² intensity, and developed with a KOH aqueous solution to form a pattern on the photoresist layer.

Example 6: Metal Pattern Formation on Flexible Substrate

After depositing a 2 nm Ti layer as an adhesion promoter on the PDMS substrate, a 20 nm Au layer was formed thereon. Subsequently, a photoresist layer was formed on the metal layer using a spin casting method with a thickness of 400 nm. The soft photomask prepared in Example 1 was placed on the photoresist layer, exposed to 100 sW / cm ² intensity, and developed with KOH solution to form a pattern on the photoresist layer. Subsequently, the Au layer was etched using KI aqueous solution, and then the photoresist layer was removed with acetone to form a pattern of Au layer on the PDMS substrate.

Optical micrographs of the surface of the metal pattern obtained through such a method are shown in FIGS. 5 and 6. As can be seen from FIG. 5 and FIG. 6, it can be seen that the resolution of the pattern is high, the uniformity is excellent, and damage such as cracks hardly occurs.

Example 7: Fabrication of Organic Electroluminescent Device

In the method of Example 6, an electrode of the organic EL device was manufactured as follows.

After the PDMS layer was formed on the base glass plate, a 2 nm Ti layer was deposited on the PDMS substrate as an adhesion promoter, and then a 20 nm Au layer was formed thereon. Subsequently, a photoresist layer was formed on the metal layer using a spin casting method with a thickness of 500 nm. The soft photomask prepared in Example 1 was placed on the photoresist layer, exposed at 200 sW / cm 2 intensity for 10 seconds, and developed with a KOH aqueous solution to form a pattern on the photoresist layer. Subsequently, the Au layer was etched using KI aqueous solution, and then the photoresist layer was removed with acetone to form a pattern of Au layer on the PDMS substrate. The formed pattern was observed on an optical microscope and shown on the right side of FIG. 7.

Separately, an ITO (indium tin oxide) layer was formed on the glass substrate, and a light emitting layer was further formed thereon.

The PDMS substrate having the Au layer pattern formed thereon was laminated using a van der Waals attraction to the light emitting layer, thereby completing an organic EL device. In the left figure of FIG. 7, an electroluminescent pattern having a line width of 800 nm can be seen. In the left figure of FIG. 7, an electroluminescence pattern having a line width of 800 nm can be seen.

Comparative Example 1: Pattern formation using a conventional photomask on a flexible substrate

In Example 5, instead of using the soft photomask according to the present invention, a pattern was formed by employing a general hard photomask.

In this case, it can be confirmed through a microscope that the quality of the pattern is degraded due to cracks.

Comparative Example 2: Fabrication of Organic Electroluminescent Device

In Example 6, instead of using the soft photomask according to the present invention, an electrode for an organic light emitting device was manufactured by employing a general hard photomask.

In this case, it was confirmed electrically by using a multimeter and a current-voltage meter that a crack or the like does not flow the device current.

The present invention provides a soft photomask for photolithography, which enhances adhesion to the photoresist layer and suppresses pattern damage such as cracks even when a flexible substrate is used. Therefore, when the pattern is formed using the same, the quality of the pattern, such as the homogeneity of the pattern is improved, and the resolution can be increased, which is particularly useful for manufacturing flexible electrodes of display devices such as organic electroluminescent devices, and can be employed for manufacturing other semiconductor devices. Do.

Claims (30)

A soft photomask for photolithography, comprising a light-transmitting elastomer, wherein a pattern is formed on one surface thereof. The soft photomask for photolithography according to claim 1, wherein the light transmitting elastomer has a glass transition temperature below room temperature. The method of claim 1, wherein the light transmitting elastomer is at least one selected from the group consisting of polydimethyl siloxane, nitrile rubber, acrylic rubber, polybutadiene, polyisoprene, butyl rubber, and poly (styrene-co-butadiene). A soft photomask for photolithography, characterized by the above-mentioned. The soft photomask of claim 1, wherein the pattern forming material is the light transmissive elastomer or the light impermeable layer. The soft photomask for photolithography according to claim 1, wherein a light impermeable layer is further formed on the recessed part (concave part) or the recessed part (projection part) of the pattern formation surface. The flexible photomask for photolithography according to claim 4 or 5, wherein the light impermeable layer is a metal layer or an organic material layer. 7. The flexible photomask for photolithography according to claim 6, wherein the organic material layer is a low molecular layer, a polymer layer, a carbon black layer or a silver paste layer. The soft photomask for photolithography according to claim 6, wherein the light absorption band of the organic layer is 200 to 450 nm. 7. The flexible photomask for photolithography according to claim 6, wherein the metal layer comprises at least one metal selected from the group consisting of Au, Ag, Cr, Al, Ni, Pt, Pd, Ti, and Cu. The soft photomask for photolithography according to claim 4 or 5, wherein the light-transmissive layer has a thickness of 1 to 500 nm. The soft photomask of claim 1, wherein the pattern has a height of 100 nm to 1 μm. Manufacturing a master substrate having a pattern formed thereon; Adding a mixture of an elastomeric precursor and a crosslinking agent on the master substrate; And After polymerizing the elastomeric precursor, separating the mask formed on the master substrate. The method of claim 12, further comprising: depositing a metal on a surface on which the pattern on the mask is formed; And A method of manufacturing a soft photomask for photolithography, further comprising the step of removing the metal layer formed on the convex portion. The method of claim 12, further comprising contacting an adhesive polymer solution, a carbon black paste, or a silver paste on the surface of the concave portion where the pattern on the mask is formed. Forming a silicon-based elastomer layer; Adhering a shadow mask on the layer; And Method for producing a flexible photomask for photolithography comprising the step of vacuum-depositing a metal or organic material. Forming a photoresist layer on the base substrate; Contacting the surface on which the pattern of the soft photomask according to any one of claims 1 to 11 is formed with the photoresist layer by soft close contact; And And exposing the pattern to form a pattern. The method of claim 16, further comprising: forming a pattern forming metal layer first before forming the photoresist layer, and then etching the metal layer using the patterned photoresist layer and then removing the photoresist layer. Method for forming a fine pattern, characterized in that. The method of claim 16, wherein when the photoresist is positive, a portion corresponding to a recess of the soft photomask is removed to form a pattern having the same shape as the protrusion. The method of claim 16, wherein when the photoresist is negative, a pattern having the same shape as a recess of the soft photomask is formed. The method of claim 16, wherein the base substrate is glass, plastic, rubber, or elastomer. The method of claim 20, wherein the base substrate is a silicon-based elastomer. The method of claim 16, wherein the metal layer for pattern formation comprises an adhesion promoter layer. 23. The method of claim 22, wherein the adhesion promoter layer is a Ti or Cr layer of 1 to 5 nm. The method of claim 16, wherein the pattern forming metal layer comprises at least one metal selected from the group consisting of Au, Ag, Al, Pd, and Pt. A display device electrode comprising a fine pattern formed according to any one of claims 16 to 24. The electrode for a display element according to claim 25, wherein the base substrate is a flexible type. An electrode for a display element according to claim 25, wherein the base substrate is glass, high quality silica glass, plastic, rubber, or elastomer. 28. The electrode of claim 27, wherein the base substrate is an elastomer. 29. An electrode for a display element according to claim 28, wherein said elastomer is polydimethyl siloxane. An organic electroluminescent device comprising the electrode for display elements according to any one of claims 24 to 29.

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